Apparatus and method for controlling refrigeration



July 23, 1935. E. J. D ILLMAN 2,003,563 I APPARATUS AND METHOD FORCONTROLLING REFRIGERATION Filed Oct. 14, 1931 Ia, l4 u 47 F131 |3 a3 as/4-6 84- an 33 a 9 .9 a0 5 n as a 29 I6 4| as 38 39 a1 a1 36 35 4a 34 a:2 415 30 l 45 {07, 6m w" u v I v Patented July 23, 1935 PATENT orriceAPPARATUS AND METHOD FOR CON- TROLLING REFRIGERATION Earnest J. Dillman,Detroit, Mich, assignor to Detroit Lubricator Company, Detroit, Mich, aCorporation of Michigan Application October 14,

16 claims.

ferential, the evaporator may be operated at its.

maximum capacity and therefore the system embodying the evaporator willbe maintained at maximum eificiency. Should the temperature diilerentialdecrease substantially below that at which maximum capacity is obtained,then liquid refrigerant is liable to enter the return or suction lineand be drawn back to the compressor. More particularly my methodcontemplates con- I trolling the admission of the refrigerant medium tothe evaporator in accordance with the maintenance of a substantiallyconstant temperature difierential, so that the temperature diiferentialwill be maintained substantially constant by the controlled evaporationof the admitted refrigerant medium.

The invention consists in the method and the apparatus for carrying thesame into efiect, to be more fully described hereinafter, and thenovelty of which will be particularly pointed out and distinctlyclaimed.-

In the accompanying drawing, to be taken as a part of thisspecification, I have fully and clearly illustrated one embodiment of myinven tion, in which drawing-- Figure 1 is a diagrammatic view of arefrigerating system embodying my invention, and

Fig. 2 is a view in longitudinal, central section of a valve employed inthe system.

Referring to the drawing by characters of reference, I designates anevaporator or cooling element which may be of the coil type, having arefrigerant medium supply or feed line or conduit 2 and a return orsuction line or conduit 3. The

supply line 2 leads from a receiver 4 fed by a condenser 5 connected tothe outlet or discharge side of a compressor 6 to the inlet of which thereturn line 3 leads and is connected. The compressor may be driven by anelectric motor I having the usual condenser cooling fan (not shown). Themotor is controlled by a pressure switch 8 responsive to variation inpressure in the return line 3 and connected in series circuit 1931,Serial No. 568,664

in the electric leads 9, 50 of the motor, thereby to start and stop themotor and therefore the compressor at predetermined desired refrigerantmedium pressure limits. In the supply conduit 2 is a valve means IIwhich controls the admission of refrigerant medium to the evaporator I.

This valve means I I is shown in detail in Fig. 2, and comprises athermostatic expansion valve having a temperature responsive bulb I2containing or charged with a volatile fluid such as methyl chloride, andwhich is rigidly secured by clamping means I3 in intimate heatconductingrelation to the refrigerant medium return line 3 at a point closelyadjacent the evaporator and as near thereto as practicable. The bulb I2is connected by a conduit or tube I4 to the interior of -a chamberedelement I5 which is rigidly supported by and preferably a part of thevalve means I I. The element I5 comprises an actuating member or powerelement having a movable head or wall I6 which is hermetically securedandsealedat its periphery to one end of an expansible-collapsibleelement H, such as a circumferentially corrugated, substantiallycylindrical, resilient, metallic bellows having its other end closed andsealed to the periphery of a plate or supporting member I8 which isapertured to receive the conduit or tube l4 to whichthe member I8 isrigidly secured and sealed, as at I9. The end of tube II has fixedthereto a guide member or sleeve which is reciprocably supported in thebore of a plug member 2| fixed in a central aperture in the base of acap member 22. The plug member 2| is externally and internally threadedoutside the cap member to receive an adjustment nut 23 through whichtube ll extends, and which is threaded into the bore of member 2 I, andalso to receive an external packing nut 24 to retain packing 25 inposition to prevent flow through the plug bore around nut 23. Within theelement I5 is an expansion member 26, preferably a coil spring undercompression and acting to expand the bellows and maintain sleeve 20 inengagement with adjustment nut 23. The head I6 is preferably indented orconcave inwardly at its center portion to retain one end of spring 26 inposition, the other end of the spring being positioned by the platemember I8 and sleeve 20. The cap member 22 is seated on and sealed to ahollow supporting member 2'! which is of insulating material such asbakelite. Within the member 21 is a transverse partition 28 having acentral guide aperture 29 alined with the indentation in the bellowshead and for ,a purpose to be described. The member 21 is mounted on avalve casing or body 30 and is secured and sealed to a continuous flangeor extension 3|, preferably cylindrical, on the valve casing. Securedand hermetically sealed to the flange 3| is a pressure responsive means,including an expansible-colla-psible member 32 such as acircumferentially corrugated, substantially cylindrical, resilient,metallic bellows which extends into the hollow supporting member 21.Secured and hermetically sealed to the free end of the bellows is asubstantially cup-shaped head or end wall 33 which extendslongitudinally through the bellows into the valve casing, and whichcarries a yoke member or arm 34 fixed thereto by means of a post 35extending through alined apertures in the head'33 and member 34. Thepost 35 has a flange 36 which seats on the head 33 and is sealed theretoby solder or the like to prevent leakage from the casing around thepost. Screw-threaded on the post within the cupshaped head is a sleevemember 31 having a lateral flange 38 at its free. end against whichabuts one end of a coil spring 39 surrounding the sleeve member. seatson a supporting member 40 mounted on the end of flange 3|, such that thespring 39 is held under compression against the flange 38 and normallytends to expand the bellows 32. The top end of post 35 is recessed toreceive one end of a thrust rod or member 4| which extends through theguide aperture 29, and which seats at its other end in the indentationor concavity in the bellows head l6. Within the valve casing is a bossor extension 42 extending transversely to the longitudinal axis of rod4| and having an 'the yoke member 34 which extends around the.

extension 42. In the passage 43 is a strainer member 46 secured inposition by a nipple 41 which is secured and connected to the supplyconduit 2. The casing has an outlet 48 communicating with the interiorof bellows 32 and connected by a nipple or the like (not shown) to theevaporator inlet.

The operation of the system is as follows: With a temperaturedifferential of eleven and one-half degrees Fahrenheit between thetemperature of evaporation of the refrigerant medium in the evaporatorand the temperature of the return or suction line at the evaporator, theevaporator will be operating at maximum capacity. By maintaining thistemperature difierential for all evaporator temperatures, the evaporatorwill be maintained at maximum capacity and the system at maximumefliciency. This temperature diflerential may be maintained bycontrolling the admission of refrigerant medium to the evaporator inaccordance with the maintenance of the predetermined differential. If,for example, the refrigerant medium employed is methyl chloride, thenwith evaporation of the refrigerant medium in the evaporator occurringat say, 135 F., the evaporator will be at maximum capacity when thetemperature of the return line at a point near the evaporator is 25 F.At these temperatures the valve 45 should be seated or closed with theforce tending to open the valve balancing the force tending to close thevalve, so that if there is any increase in the temperature of the returnline, and therefore of the bulb l2, at the evaporator,

The other end of the spring 39- or of there is any decrease in thetemperature of evaporation within the evaporator, the valve 45 will beopened to admit refrigerant medium to the evaporator and maintain thedesired differential. In order to maintain this differential for alloperating temperatures of the evaporator, the change in force exerted bythe power element l5 for each degree change of temperature must be lessthan the change in force exerted by the bellows 32 for each degreechange of temperature, and if, for example, the ratio in square inchesof the effective areas of the element l5 and the bellows 32 is as 1.00to 1.16, then the desired temperature differential will be maintainedfor methyl chloride refrigerant. The pressure or force exerted by theelement |5 at a bulb temperature of 25 F. will be for methyl chloride17.5 pounds, as the effective area of element i5 is unity, and the forceexerted by the bellows 32 will be in accordance with the temperature ofevaporation of the refrigerant in the evaporator, which at 135 F. is10.5 pounds per square inch for methyl chloride, so that the forceexerted by bellows 32 tending to close the valve 45 will be 12.18pounds. Therefore in order to have the valve in balanced closedposition, the springs 26 and 39 are adjusted by the nut 23 to exert aresultant force equal to the difference between the opposing forces,namely, a force of 5.32 pounds acting to seat the valve. When the systemis started in operation from a warm condition by closing of the circuitof motor with the temperature of -the bulb l2 at say, F., the forceexerted by the ture, there should be a differential of F. or

the temperature in the evaporator should be 685 E, which corresponds toa refrigerant medium pressure with methyl chloride of 57.2 pounds persquareinch. This force acting through the be]- lows 32 to close valve 45will, due to the effective area of bellows 32, be exerting a force onrod 4| of 66.43 pounds, which added to the force exerted by the springs26 and 39 of 5.32 pounds equals 71.75 pounds, so that the valve is heldin balanced closed position. When the compressor reduces the pressure inthe evaporator below 57.2 pounds per square inch, the power element |5being subject to a temperature of 80 F. will act to open valve 45 toadmit refrigerant medium to the evaporator, the medium expanding thereinto increase the pressure and close the valve. This will, however.decrease the temperature of the return line and therefore of the bulb,so that the pressure in the evaporator may be further reduced by thecompressor before the valve 45 will be opened. This gradual step by stepreducly constant temperature differential will continue until the lowpressure limit is reached, corre-' sponding to a temperature of, say, 25F. at the bulb l2, when the switch 8 will stop the motor and compressor.1 As the bulb l2 warms, tending to open valve 45, the refrigerant mediumin the evaporator will also expand to increase the evaporator pressurewhich acting through bellows 32 will prevent the valve from opening. Thetemperature of the evaporator increases until the predetermined desiredmaximum pressure in the return line is reached, when switch 8 will againturn on the motor I to complete a cycle of operation and start adecrease of evaporator temperature.

From the foregoing, it is apparent that the valve means ll operates tomaintain a constant temperature differential between the temperature ofthe refrigerant medium in the evaporator and the temperature of thereturn line at the evaporator, so that the evaporator is maintained atmaximum operating capacity, regardless of the temperature in theevaporator.

It is also to be noted that the number of degrees difference, or thetemperature differential, may be increased by an increase in .the aboveratio of effective bellows areas, and may be de-.

creased by a decrease in the said ratio.

What I claim and desire to secure by Letters Patent of the United Statesis:

-1. A device'of the character described, comprising a valve casinghaving an inlet and an outlet, a valve in said casing operable tocontrol flow therethrough, means normally acting to move said valvetoward closed-position, an expansible-collapsible member operativelyconnected to said valve and acting upon increase of pres sure in saidcasing to urge said valve toward closed position, temperature responsivemeans including an expansible-collapsible member, and a thrust memberpositively held in engagement with said last-named member and said valveand operable upon increase of temperature to urge said valve toward openposition, said last-named expansible-collapsible member being of lesseffective cross-sectional area than said first-namedexpansible-collapsible member.

2. A device .of the character described, comprising a valve casinghaving an inlet and an temperature increase to said valve, saidsecondnamed bellows member being of less eifective cross-sectional areathan said first-named bel lows member whereby said valve will becontrolled by a substantially constant temperature differin theevaporator and the temperature at said given point so that the systemwill be kept at maximum operating capacity. v

4. The method of operating a refrigerating system which comprisesdecreasing the temperature of the evaporator at a. substantiallyconstant rate while maintaining a predetermined constant temperaturediiferential between the temperature of the refrigerant in theevaporator and the tem' perature of the return or suction line adjacentthe evaporator, and regulating the rate of admission 2 of refrigerant tothe evaporator in accordance with and dependent onboth variation ofrefrigerant temperature in the evaporator and variation of return linetemperature adjacent the evaporator throughout the range of temperaturedecrease whereby to maintain the evaporator wet throughout its internal.length and to obtain the maximum operating capacity-of the system.

. 5. A device for maintaining in a refrigerating system a substantiallyconstant temperature differential between the temperature of therefrigerant' in the evaporator and the temperature of the refrigrantreturn or suction line adjacent the evaporator which comprises anautomatically operable valve controlling admission of refrigerant to theevaporator, a pressureoperated element responsive to and exerting aforce in accordance with the temperature of the refrigerant return line,a pressure operated element responsive to and exerting a force inaccordance with the temperature of the refrigerant in the evaporator, athrust member for transmitting the force of said first-named element tosaid second-named element, means for transmitting the forces exerted bys'aid first-named and said second-named elements to said valve, saidsecond-named element having a greater efiective pressure responsive areathan said first-named element whereby said second-named element willexert a greater force than said first-named element for a givenrefrigerant temperature thereby to compensate for increase in pressuredifference of the refrigerant for a given temperature difference of therefrigerant as the temperature of the refrigerant increases.

6. A device of the character described, comprising a valve casing havinganinlet and an outlet and containing a valve port, a valve membercooperable with said port, a pressure responsive element movable inresponse to change of pressure in said casing and operatively conncct-'.of said cap member, a thrust member extending through said aperture andpositioned between and at one end engaging said expansible-collapsiblecasing and at its other end engaging said element, and a coil springsurrounding said thrust member and acting through said thrust member tooppose expansion of said expansible-collapsible casing.

'7. A device of the character described, comprising a valve casinghaving an inlet and an outlet and containing a valve port, a valvemember cooperable with said port, a pressure responsive element movablein response to change of pressure in said casing and operativelyconnected to said valve member, a hollow member secured on said casingand overlying said element, said hollow member having guide means, anexpansible-collapsible casing within said hollow member, a tubularmember projecting from said cxpansible-collapsible casing andreciprocable in said guide means, an adjustment member carried by saidhollow member and engaging said tubular member to adjust saidexpansible-collapsible casing, a bulb element having condut meansopening into said expansible-collapsible casing through said tubularmember, and a thrust member operatively connecting saidexpansible-collapsible casing and said valve member.

8. A device of the character described, comprising 'a valve casinghaving an inlet and an outlet and containing a valve port, a valvemember cooperable with said port, a pressure responsive element movablein response to change of pressure in said casing and operativelyconnected to said valve member, a hollow member secured on said casingand overlying said element, said hollow member having guide means, anexpansiblecollapsible casing within said hollow member, a tubular memberprojecting from said expansiblecollapsible casing and reoiprocable insaid guide means, an adjustment member carried by said hollow member andengaging said tubular member to adjust said expansible-collapsiblecasing, a helical coil spring within said expansible-collapsible casingand urging said tubular member into engagement with said adjustmentmember, a bulb element having conduit means opening into saidexpansible-collapsible casing through said tubular member, and a thrustmember operatively connecting said expansible-collapsible casing andsaid valve member.

9. A device of the character described, comprising a valve casing havingan inlet and an outlet and containing a valve port, a valve membercooperable with said port, a pressure responsive bellows element movablein response to change of pressure in said casing and operativelyconnected to said valve member, a hollow member secured on said casingand overlying said element, a tubular spring abutment member rigid withand supported within said hollow member, said abutment member extendinginto said bellows and having an annular internal shoulder, said hollowmember having an expansible-collapsible chamber with a movable wall, athrust member extending through said tubular member and operativelyconnecting said wall and said element, said thrust member having ashoulder, and a helical coil spring within said tubular member andsurrounding said thrust member, said spring being heldunder compressionbetween said shoulders and opposing expansion of said chamber.

10. A device of the character described, comprising a valve casinghaving an open side and having an inlet and an outlet, a valve memberreciprocable in and controlling flow through said casing, a metalbellows having one end secured to said casing and having a head closingand sealing its other end, means for transmitting move- .valve bodyhaving a passageway therethrough, a

ment from said head to said valve member, a hollow member on saidcasing, a tubular spring abutment member within said hollow member and.

having a laterally extending supporting .fiange, said abutment memberextending into said bellows and having an internal annular shoulderadjacent said head, a metal bellows within said hollow member and spacedfrom the side walls thereof, said second-named bellows'having oppositelypositioned heads, a rigid thrust member cally secured and sealed to saidcasing and having a head. closing and sealing its other end, means fortransmitting movement from said head to said valve member, a hollowmember surrounding the open side of said casing and having screwthreadedengagement therewith, a tubular spring abutment member within saidhollow member and having a laterally extending supporting flange, saidabutment member extending into said bellows and having an internalannular shoulder adjacent said head, a metal bellows within said hollowmember and spaced from the side walls thereof, said second-named bellowshaving oppositely positioned heads, a rigid thrust member extendingthrough said tubular abutment member and having one end engaging saidfirstnamed head and having its other end engaging one of said oppositelypositioned heads, adjustment means carried by said hollow member andcooperable with other of said oppositely positioned heads to regulatethe expansion of said secondnamed bellows, a bulb element communicatingwith the interior of said second-named bellows, and a helical coilspring within said tubular member and surrounding said thrust member,said spring having one end seated on said shoulder and having its otherend acting on said thrust member to oppose expansion of said secondnamedbellows.

12. In a thermostatic valve including a valve casing, a valve in saidcasing, a projecting portion, a sealing bellows supported by saidportion, and means extending from said bellows to said valve, anactuating element mounted on said casing and said portion, said elementcomprising a housing snugly fitting said projecting portion, a walldisposed transversely of said housing dividing the same into twochambers, said wall being formed with an aperture at the center thereof,an actuating pin positioned in said aperture; said pin extending intosaid sealing bellows to operate the same, a power bellows mounted insaid'housing and in the other chamber thereof, one end of said powerbellows being in contact with the opposite end of said actuating pin,and means extending through the end oi! said housing opposite saidsealing bellows for adjusting'said power bellows.

.13.. A refrigerant control device comprising a.

valve in said body and controlling flow through said passageway, saidbody having an open side, a bellows member closing and sealing saidside, means operatively connecting said valve to said bellows member foroperation thereby, a housing secured to said body and enclosing saidbellows member and said open side, a thermostatic bellows member in saidhousing and, responsive to temperature conditions, a supporting memberin extending through saidtubular abutment mem- ;members, said supportingmember having a tulbular central portion terminating in an internal berand having one end engaging said first-namedhead and having its otherend engaging one' ot said oppositely positioned heads, a bulb element}communicating with the interior of said second-f; named bellows, and ahelical coil spring within said tubular member and surroundingsaid-thrust member, said spring having one end seatedon" said shoulderand having its other end actingon said thrust member to oppose expansionof said second-named bellows.

11. A device of the character described, comprising a valve casinghaving an open side and having an inlet and an outlet, a valve memberreciprocable in and controlling flow through said casing, a metalbellows having one end hermetisaid housing and positioned between saidbellows shoulder adjacent the head of said sealing bellowsmember, athrust member in and extending through said tubular portion and havingits ends engaging said bellows members to transmit iinovementtherebetween, said thrust member having a lateral shoulder. facing saidinternal shoulder, and a spring in said tubular portion and held undercompression between said shoulders and urging said thrust membertowardsaid thermostatic bellows member.

14. A refrigerant control device comprising a ,valve body having apassageway therethrough, a valve in said body and controlling flowthrough said passageway, said body having an open side, a bellows memberclosing and sealing said side, means operatively connecting said valveto said bellows member for operation thereby, a housing secured to saidbody and enclosing said bellows member and said open side, athermostatic bellows member in said housing and responsive totemperature conditions, a supporting member in said housing andpositioned between said bellows members, said supporting member having atubular central portion terminating in an internal shoulder adjacent thehead of said sealing bellows member, a thrust member in and extendingthrough said tubular portion and having its ends engaging said bellowsmembers to transmit movement therebetween, said thrust member having alateral shoulder facing said internal shoulder, a spring in said tubularportion and held under compression between said shoulders and urgingsaid thrust member toward said thermostatic bellows member, and anadjustment means carried by said housing and operable to regulate theresponse of said thermostatic bellows member.

15. A device of the character described, comprising a valve casinghaving an open side and having an inlet and an outlet, a valve memberreciprocable in and controlling flow through said casing, a metalbellows element providing a closure for the open side of said casing andhaving one end secured to said casing at the margin of said opening andhaving a closed headsealing its other end, means for transmittingmovement from said head to said valve member, a hollow valve casingextension having its inner end open and detachably connected to thevalve casing at the margin of its said open side and closed at itsopposite end except for a guide passage therethrough, a second metalbellows element within said casing extension adjacent the outer end ofthe latter and having an outer end head with a tubular extension, saidtubular extension being adjustably received in said guide passage, saidsecond bellows element having a closed inner end head opposed to saidfirst-named head, an external thermo-responsive bulb, a conduitconnection between said bulb and the interior of said second bellowselement and passing through said tubular extension, said casingextension comprising partition means between the two bellows elementsand separable from the portion of the casing extension enclosing saidsecond bellows element, said partition means comprising a cupshapedportion extending into the first mentioned bellows element and formedwith an aperture at its bottom, a thrust member extending through saidcup portion and into engagement with the opposed heads of said bellowselements and having a lateral surrounding flange adjacent the top ofsaid cup portion, and a helical coil spring surrounding said thrustmember and acting between said flange and the bottom of said cup portionto exert resilient force on the closed inner head of said second bellowselement opposing the expansion of the latter.

16. In a refrigerant control device, a body, a valve therein, a sealingbellows supported by the body and operable to actuate said valve, athermostatic bellows responsive to temperature conditions, a housingsecured to the body and enclosing both of said bellows, a wall structurein the housing providing a heat insulating partition between the twobe'llows and having an axially elongated passageway therethrough, saidwall structure having an abutment in said passageway adjacent thesealing bellows, a plunger extending through said passageway andconnecting the two bellows and having a lateral spring abutment adjacentthe thermostatic bellows, a spring in said passageway and acting betweensaid abutments to urge said plunger toward said thermostatic bellows,and adjustable means on said housing for compressing the thermostaticbellows against the resistance of said spring pressed plunger.

EARNE ST J. DILLMAN.

